1. Field of the Invention
The present invention generally relates to computer software. More specifically, the present invention relates to a vector-based graphics application configured to generate scale-dependent renderings of natural media styles in a vector graphics drawing.
2. Description of the Related Art
The term computer-aided design (CAD) generally refers to a broad variety of computer-based tools used by architects, engineers, and other graphics and design professionals. Vector graphics, also called geometric modeling or object-oriented graphics, refers to the use of geometrical primitives such as points, lines, curves, and polygons, which may be based upon mathematical equations, to represent images in computer graphics. Vector graphics are distinct from raster graphics. In raster graphics applications, images are represented as a collection of pixels or dots.
With typical vector-based design programs, like Autodesk® Impression™, scaling a given vector drawing is typically not a problem. As graphics are scaled up or down, all the attributes of each object are usually scaled proportionally. In most cases, this results in an excellent representation of an object at any size.
A common feature of vector graphics applications is the ability to incorporate graphic styles in a vector-based drawing. A graphic style is a set of reusable appearance attributes. Graphic styles allow a user to quickly change the look and feel of an object. For example, a user can change an object's fill and stroke color, alter its transparency, and apply various effects in one step. An example of a graphic style includes a pencil graphic style, wherein the strokes of the graphic style represent a pencil being used on paper to shade an area. A pencil graphics style, as opposed to a solid color fill, more closely represents the actual appearance of pencil on paper. A pencil graphics style may be used by an architect who wishes to create a vector graphics drawing that resembles a hand-drawn architectural plan.
Natural media graphic styles (e.g., pencil strokes) have properties making them somewhat more complex than other vector graphics application features. This is readily apparent when attempting to scale a vector drawing that includes graphic styles applied to drawing geometry. Strokes of a graphic style are composed of parameters meant to simulate traditional media, like instrument hardness, tip angle, stroke emphasis, paper grain, and features of the media, such as whether a stroke simulates a pencil, a pen, a watercolor brush, chalk, etc. These graphic style parameters do not scale proportionally with how an artist would typically create a drawing by hand. For example, while an artist working with actual media may use a sharper pencil when drawing a smaller object, the sharper pencil would not normally be proportionally smaller or sharper. Also, if the artist drew an object and then wanted to draw the same object but three times larger, the artist would not typically change the paper for the larger drawing, but would only change the drawing stylus. Similarly, paper grain, does not scale at all as the artist draws smaller/larger representations of the same image.
For these reasons, scaling vector drawings with graphic styles has proven to be challenging. Currently, the most common approach to scaling graphic style objects is to either scale all of the graphic style parameters proportionately, or, in the alternative, not scale any of the graphic style parameters. When all of the graphics style parameters are scaled proportionately, the drawing no longer maintains a natural media appearance. Likewise, when none of the graphic style parameters are scaled, the drawing may look unrealistic, mechanical, or may lose its natural appearance. Styles created at one scale can become either illegible at smaller scales or devoid of the visual appearance that provides the “hand drawn look” at larger scales. Further, it is quite burdensome for a user of a vector-based graphics application to create unique graphic styles for all of the different scales or sizes of drawings that the user may create.
Accordingly, there remains the need in the art for a technique for generating scale-dependent renderings of natural media graphic styles in a vector drawing.